The invention concerns a belt grinder comprising a pressure beam with a plurality of pressure pads arranged adjacent to each other, said pressure beam being aligned transversely to the direction of the workpiece and exposed to a variable contact pressure and with a grinding belt being guided over it for the processing of the surface of the workpiece.
Belt grinders of this type have been known for a long period of time. They are capable of processing workpieces with complex surface configurations, if the arrangement of the pressure pads is such that they may be moved individually from an ineffective into an effective position. In this manner, the grinding belt is pressured onto the workpiece only in the area required by the shape of the workpiece.
A wide belt grinder of this type is known from German Gebrauchsmuster No. 82 23 923.1. A switch is associated with each pressure pad in the inlet area of the belt grinder. The switch is actuated whenever the workpiece passes over the appropriate location of the inlet area. A signal indicating that the pressure pad corresponding to this location is to be moved into its effective position is thereby transmitted to the pressure beam. For this purpose, an actuating voltage is conducted to an electromagnet connected with the pressure beam, so that the pressure pad is brought into its contact position (with a time delay in relation to the switch). The top side of the electromagnet rests on a pressure hose which, in turn, is supported stationarily at its upper side. By controlling the pneumatic pressure in the pressure hose, the contact pressure of the pressure beam may be regulated. The hose extends over the entire width of the pressure beam, thereby affecting all of the pressure pads uniformly.